China Youth Daily·China Youth Daily reporter Li Si
"It can be clearly said that this El Niño event is the strongest since monitoring records began." On the afternoon of November 3, Zhao Junhu, chief forecaster of the National Climate Center, conducted an online live broadcast with meteorological experts from eight locations across the country to interpret the impact El Niño will have on my country's climate pattern and how different regions will be affected.
El Niño “charges first and then discharges”, and its impact will be greater the following year
Zhao Junhu said that since 1950, a total of 22 El Niño events have occurred in the equatorial central and eastern Pacific, "this year is the 23rd time." Not long ago, the National Climate Center confirmed that an "eastern-type super strong El Niño event" had officially formed in September this year, and is expected to reach its peak around November to December. Previously, there have been only three super strong El Niño events in history, which occurred from 1982 to 1983, 1997 to 1998 and 2014 to 2016.
"This year's super El Niño developed very rapidly." Zhao Junhu said that it only took 5 months to reach the super strong standard this time, while the previous three times took about 7 to 15 months. The equatorial central and eastern Pacific entered an El Niño state in May this year, and the intensity of this year's event exceeded the previous three.
He introduced that the lagging influence of El Niño comes from the "memory" of the ocean: atmospheric circulation changes quickly, but sea temperature changes very slowly, and seawater heats and cools slowly. El Niño first stores huge energy in the central and eastern Pacific. "In winter and the following spring, just like a power bank charging first and then discharging, the heat is gradually dispersed to the Indian Ocean, the tropical North Atlantic and other regions. The three oceans jointly interact through sea and air, and then slowly release heat to the atmosphere, affecting the global climate. This process lasts for about half a year."
At the November press conference of the China Meteorological Administration, Gao Rong, deputy director of the National Climate Center, pointed out that this El Niño event is the strongest since monitoring records began, and is expected to reach its peak in late autumn and early winter, which will have a significant impact on my country's climate this winter and next spring.
The National Climate Center predicts that the overall temperature across the country will be higher this winter, but the frequency of cold waves will be slightly higher, and the temperature will fluctuate greatly. There will be strong cooling and snowfall in the north, and the risk of periodic low-temperature rain, snow, and freezing in the south will be prominent. Except for the low temperatures in northeastern Inner Mongolia and the western part of Northeastern China, the temperatures in most other parts of the country are close to normal or higher for the same period of the year, and show the characteristics of cold winter in the first and warm winter in the second. Periodic strong cooling and strong warming events are frequent in December and January.
In terms of precipitation, there is generally more precipitation across the country. Heavy snowfalls occur frequently in most areas in the north. There is significantly more precipitation in the south. Among them, there are periods of low-temperature rain, snow, and freezing weather in eastern and southern China, central and southern China, northern South China, and eastern southwest China.
"Next summer, floods will be more severe than droughts in the eastern region. There will be significantly more precipitation in the Yangtze River Basin, and there may be heavier floods. Southern South China, southern Southwest China, Huanghuai and other places may have less precipitation, and they need to prevent high temperatures and droughts. Temperatures in most parts of the country are obviously higher, and high-temperature heat waves are stronger and wider in scope." Zhao Junhu said.
During the live broadcast, Zhao Junhu specifically reminded the public to be wary of "three misunderstandings" about El Niño. "This winter must be a warm winter" is the first misunderstanding. He said: "In the winter of El Niño development years, the national temperature is generally high. This is a seasonal average concept, but it does not mean that there are no strong cooling and cold waves in winter. Strong cooling and cold waves refer to weather processes. Historically, super cold waves occurred in January 1998 and January 2016."
Taking El Niño as the direct cause of a certain disaster is the second misunderstanding. El Niño increases the probability of extreme weather, but not every heavy rain, high temperature, and typhoon is caused by it. A simple comparison between this year's super El Niño and the previous three super El Niño events is the third misunderstanding. "In the context of global warming, climate changes. The climate background corresponding to each El Niño event is different, and the impact will not be replicated."
How the "warm signal" from the distant Pacific changes temperatures, precipitation and typhoons in various places
Will this climate event that occurred in the distant Pacific cross mountains and seas and affect the vast land in northwest my country? Liu Jing, a senior engineer at the Climate Center of the Xinjiang Uygur Autonomous Region, pointed out that Xinjiang is located in the hinterland of the Eurasian continent and has a typical arid and semi-arid climate. El Niño, as a "warm signal" of sea temperature anomalies in the tropical Pacific, usually does not directly affect the local climate in Xinjiang, but plays an indirect modulating role through physical processes such as westerly teleconnections and the Indian Ocean lag effect.
"We consider that the overall temperature in Xinjiang this winter will be warmer, but El Niño is not the only factor that determines Xinjiang's winter temperature. The Arctic Oscillation, North Atlantic Oscillation, etc. may trigger periodic extreme cold events." Liu Jing said.
Based on Chongqing's regional climate and three-dimensional climate characteristics, Dong Xinning, a senior engineer at the Chongqing Climate Center, pointed out: "Under the background of super strong El Niño, the probability of warm winter in Chongqing is not high, but the characteristics of periodic fluctuations in cold and warm temperatures are relatively obvious."
If time passes to next summer, some areas of our country may experience high temperature and heat waves. Xiao Ying, deputy chief of the Hubei Provincial Climate Center, explained that in the year following a super strong El Niño, the western Pacific subtropical high is likely to become stronger and westward, increasing the probability of sustained high-temperature heat waves in Hubei.
El Niño makes the subtropical high larger and stronger. Wang Juanhuai, chief of decision-making services at the Guangdong Provincial Climate Center, pointed out that the high temperatures in Guangdong next summer will not be simply dry heat, but will often be "sauna days" - high temperatures, high humidity, poor ventilation, the perceived temperature is higher than the actual measured temperature, and it is very difficult for the human body to dissipate heat.
In terms of precipitation, Dong Xinning said that in the summer of super strong El Niño decay years, the Yangtze River Basin in my country, including Chongqing, will generally be rainier.
"El Niño, as the 'strongest signal' of interannual changes in the air-sea system, has a significant impact on the global climate." Cheng Zhi, a senior engineer at the Anhui Provincial Climate Center, pointed out, "The area between the Yangtze and Huaihe Rivers in Anhui and along the south of the Yangtze River are typical areas for plum rains in China. In El Niño decay years, the probability of plum rains being more abundant and intense is higher."
Ma Hao, chief expert of the Climate Prediction Office of the Zhejiang Provincial Climate Center, said that in the year following El Niño, the main characteristics of the Meiyu in Zhejiang are that the Meiyu begins earlier and emerges later, the Meiyu period is longer, and the amount of Meiyu is more abundant.
In terms of typhoons, "Typhoons are extremely active this summer." Zhao Junhu said that this is because the subtropical high in El Niño development years is larger, stronger, and located farther south. "We consider that the number of typhoons generated next summer will be relatively small, but the intensity will be stronger, and their paths will be mainly westward, mainly affecting the coastal areas of South China."
"During El Niño decay years, Zhejiang is also greatly affected by typhoons." Ma Hao pointed out that according to statistics, in the past three super strong El Niño decay years, Zhejiang had one typhoon in 1983, four in 1998, and six in 2016. The overall impact of typhoons was heavy.
Wang Juanhuai reminded that Guangdong has a long coastline. Once a typhoon lands or passes by at close range, there will often be "three collisions" of strong winds, heavy rains, and storm surges. In the year following El Niño, the time interval between typhoons may be longer, and the public and coastal enterprises are prone to paralysis. Lax disaster prevention is a hidden danger that needs to be prevented during the typhoon season.
How should agriculture, animal husbandry and fishery respond? Experts: Respond to climate uncertainty with certainty of measures
Ma Hao said that under the influence of continuous precipitation, the impact of El Niño on agriculture is obvious. "For Zhejiang, it is not conducive to the filling and harvesting of autumn harvest crops such as late rice. It will also affect the sowing of winter crops such as rapeseed and wheat. It will also lead to a decline in the quality of fruits such as citrus and strawberries, and the risk of agricultural pests and diseases will increase."
Hubei is the main rice producing area in my country. "When it rains continuously and the field humidity is high, the rice fields are highly closed and the ventilation and light transmission conditions become poor, which can easily induce sheath blight, rice blast, rice smut and various bacterial diseases." Xiao Ying said that in agricultural management, the sowing density must be reasonably controlled. degree and nitrogen fertilizer application amount, seize the key points before and after rain to dry the fields in time to control seedlings, reduce ineffective tillers, and reduce the risk of disease; disease prevention and control should pay close attention to the prevention and control window period, seize the opportunity for sunny and good weather to apply pesticides at the right time, and if there is rainfall after pesticide application, timely supplementary control is required.
Cheng Zhi also pointed out that south of the Huaihe River in Anhui is a rice-wheat rotation area, with wheat and rapeseed growing from October to May of the following year, and rice growing from May to September. In El Niño declining years, the probability of continuous rain in spring along the south of the Yangtze River is high, and rapeseed is prone to waterlogging. Excessive humidity in the field leads to root hypoxia, weakened growth, and induces diseases such as sclerotinia. The concentrated heavy rainfall in summer is not conducive to the mature harvest of winter wheat and rapeseed, affects early rice booting and grain filling, and induces rice diseases...
Liu Wei, a senior engineer at the Climate Center of the Inner Mongolia Autonomous Region, said: "El Niño changes the spatiotemporal distribution pattern of regional water and heat conditions, which has a certain impact on the growth rhythm of pasture, yield formation, and forage reserve arrangements." She suggested that when precipitation is high and sunny days are relatively scattered and short-lived, it is necessary to seize the opportunity to harvest consecutive sunny days; the development period of pasture is advanced, and harvesting is as soon as possible, so that hay nutrition will be better. At the same time, you can refer to the forecast of winter climate trends to adjust the amount of grass stock in a timely manner and reserve hay with concentrated feed to ensure the supply of forage during the winter captive period and reduce losses caused by climate fluctuations.
"Guangdong is a major province of marine aquaculture, and the impact of high temperature and high humidity is very direct." Wang Juanhuai said that high seawater temperatures lead to a decrease in dissolved oxygen in the water. Fish, shrimp, oyster rows, and cage culture are prone to hypoxic stress, causing floating heads, pond flooding, and death. Sustained warm sea temperatures can easily induce red tides and harmful algal blooms, destroy water quality, and affect the safety of aquatic products. Aquatic diseases are more likely to occur in long-term high temperature and high humidity environments, "putting greater pressure on the fisheries in western Guangdong and the Pearl River Delta coast."
Dong Xinning said that the climate system is very complex and contains many influencing factors. Although El Niño is an important factor, it is not the only influencing factor. "We can only respond to climate uncertainty with the certainty of measures" and "do our best to maintain peace."
